What exactly is the roster math for USC heading into tomorrow’s game against Utah? Assuming receiver Marqise Lee doesn’t play, but tailback Tre Madden and offensive lineman Aundrey Walker do, USC will have 50 recruited scholarship players available for the game. Three more (Nelson Agholor, Dion Bailey and Ty Isaac) are listed as either ''questionable’’ or ''possible’’ for the game. The list does not include walk-ons John Akiba, John Auran, Cody Skene and Kyle Yatabe, who were awarded one-semester scholarships at the start of the season. USC is expected to have at least 17 players unavailable for the game, including those who got hurt in spring practice. Here’s the rundown...

For the third time in the last 12 months, Josh Shaw has moved from safety to cornerback. Shaw did it once last season and once early this season, and now seems on track to start at cornerback against Utah.

``I’ll tell you one thing. I’m getting more and more used to it,’’ Shaw said with a grin. ``At times, it can be difficult. I’m playing safety for two weeks, then corner, then back to safety, then back to corner, but I welcome it. I think it’s only going to help me in the long run, and right now it’s what is best for the team.’’

Anthony Brown missed five games, then started against Notre Dame and struggled. He apparently suffered an injury in that game and hasn’t practiced this week. Torin Harris, an occasional starter, has struggled badly this season, so coaches thought their best option was to move Shaw back to cornerback.

``We really struggled at the cornerback position,’’ interim Coach Ed Orgeron said. ``When (Shaw) was there, we weren’t struggling. With some offenses, he may have to play cornerback. With some offenses, he may have to play safety. It’s a week-by-week thing.’’

USC’s secondary has struggled in recent weeks against quick-passing attacks, but Shaw said he’s confident that the unit can show improvement against Utah.

Here's the best way to put USC's final preseason depth chart in perspective... Asked about it today, Coach Lane Kiffin said he put about five seconds' worth of thought into it, and said (half-jokingly) that it was only because USC's sports-information director forced him to do so.

That said, not surprisingly, the depth chart provided almost no clarity, as it included nine positions with co-starters, tri-starters or quad-starters (which probably isn't even a gramatically correct term).

At any rate, here's the two-deep that USC released today. I've taken the liberty of, in the case of co-starters, adding on which player I expect to start against Hawaii...

USC has five practices remaining before the Aug. 29 season opener at Hawaii, and none of them will be open to reporters. So, in terms of starting positions that have yet to be settled -- quarterback, tailback, fullback, right guard, cornerback, safety -- it's all educated guesswork unless Coach Lane Kiffin decides to announce starters.

Based on fall camp, though, here's a reasonable projection at how things might look for the Trojans on the first offensive and defensive series...

How are things looking at USC fall camp, in terms of battles for starting spots? Here's a look at how things are stacking up at each position...

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OFFENSE

QUARTERBACK

We all know this one. It shouldn’t be long before Cody Kessler or Max Wittek is named the starter. Probably. Maybe. An intriguing -- albeit far less important subplot -- is whether freshman Max Browne really has a chance to win the backup job or whether he will redshirt. Almost certainly it will be the latter, unless Coach Lane Kiffin wants the loser of the Kessler-Wittek battle to transfer immediately.

The Trojans held their second scrimmage of fall camp at the Coliseum, a 68-play, decidedly one-sided affair. The first-team offense faced the first-team defense seven times. The results? One touchdown drive, plus six series in which the offense failed to record a single first down.

As expected, Cody Kessler and Max Wittek split series, but the quarterbacks’ numbers were far from equal.

Kessler finished 20 of 28 for 231 yards and three touchdowns. Wittek finished 2 of 7 for 15 yards and zero touchdowns. Why the disparity? In part because Wittek faced the dominating first-team defense four times, while Kessler faced the first-team defense only twice. But that doesn’t explain everything.

As he did in spring practice, Kessler showed greater command on the field. He checked down to running backs for short-yardage passes and didn’t throw an interception in 28 attempts -- Wittek was also interception-free -- although cornerbacks came very close to intercepting three of Kessler’s passes.

Aundrey Walker appears to have lost the left-tackle battle to Chad Wheeler, but in another surprising twist, Walker is now challenging John Martinez to be USC's starting right guard.

Martinez, a two-year starter, spent all of Wednesday's practice with the second team while Walker, who missed the early part of fall camp because of concussion symptoms, took the first-team reps. Walker, a junior, entered USC as a guard but spent the last two seasons at tackle.

Coach Lane Kiffin confirmed that there's now a full-blown competition to be USC's starting right guard.

''We're always trying to create competition, and we've had a lot of that in this camp at different spots,'' Kiffin said. ''Now we have one at guard. John and Aundrey are going to have a really good competition there.''

This is all good news for Wheeler, who rose from unknown freshman to starting left tackle. Kiffin seems comfortable with the pairing of Wheeler and left guard Max Tuerk, a starter at left tackle in 2012.